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Author Topic: Higgins Hellcat  (Read 20979 times)

GG

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Higgins Hellcat
« on: February 19, 2008, 10:17:17 PM »

I'll admit to enjoying both fast electric and warship models, so something based on torpedo boats is an obvious thing to build.  My first attempt, based on the 80 foot Elco PT boats ( Model Boats Nov 99) showed that speed, duration and handling were fine if the model weight was kept under control.  A second attempt, based on the smaller "Miami" rescue boats built in the USA, had to be constructed to about half the weight of the PT boat, resulting in the change from a 545 motor on six sub-C cells to a 400 motor on six AA cells.  The result was the same good performance and handling as before and this one was published in the June 06 issue.

A year later and another fast scale type of model was built.  Sticking with 1:32 scale and a more ambitious project was started using the "Hellcat" prototype PT boat made by Higgins.  This was smaller than the Elco model but I wanted it to be fast so a racing 500 motor and six sub-C cells were squeezed into the hull.  The result was rather faster than expected, infact it was suggested I ought to enter races with it, but the handling still safe and predictable.  To calm things down a little, the motor was replaced with a standard 540, it's still fast but I can enter steering events with more chance of sailing through obstacles rather than over them.

On the basis of these three models I've learnt that fast scale models are practical if the weight is controlled.  The Elco is about 1.5 kg and the Hellcat around 1 kg.  These are reasonable targets using balsa for the hull structure plus a little plywood, plastic but the minimum of metal.  A single motor driving a large propeller via a gear reduction seems to be the way to go for speed and duration.  I've had success using a 2:1 reduction and "X45" props with the 500 motors.  A single rudder with sufficient area to keep the model on the right heading is also essential.

With luck the editor of Model Boats will publish this plan so I might get the chance to indulge in some fast scale racing?

GlynnG
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GG

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Re: Higgins Hellcat
« Reply #1 on: February 19, 2008, 10:18:56 PM »

Whoops, one photo failed to get attached!

GlynnG
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Mark H

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Re: Higgins Hellcat
« Reply #2 on: May 30, 2008, 10:26:56 PM »

Has anybody made a Hellcat yet as the plans have recently been published in Models Boats?

I was thinking of scaling up to around 3 foot in length. Any thoughts or pitfalls that I should look out for such as motor or rudder sizes/

All help gratefully received as this will be my first scratch build
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andyn

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Re: Higgins Hellcat
« Reply #3 on: June 11, 2008, 08:03:41 PM »

I'm making your hellcat, have cut all the bits out but need to buy the propshaft before I do anything else.

Mines going to just have a straight drive 540 (not geared) as I'm after scale, not speed.

Have also built all of the cabin which is ready to be glued on as soon as I make the rest.

Any photos of it going?
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GG

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Re: Higgins Hellcat
« Reply #4 on: June 11, 2008, 10:26:53 PM »

I've no photographs of the Hellcat sailing, it's not the sort of model you can operate whilst holding both transmitter and camera!
But, if you go onto the US website, RCGroups, scroll down to the Boats section - Dock Talk - Westport Mayhem - page 13, you will find a video of my Hellcat sailing taken by Ghost 2501.
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andyn

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Re: Higgins Hellcat
« Reply #5 on: June 12, 2008, 01:08:21 PM »

adfsgj';;dhjks]0sdgh thats fast!!

I thought my Crusader was going to be quick....

Definately going to be straight drive then...
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HS93 (RIP)

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Re: Higgins Hellcat
« Reply #6 on: June 12, 2008, 01:34:43 PM »

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DickyD

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Re: Higgins Hellcat
« Reply #7 on: June 12, 2008, 01:42:42 PM »

Surprisingly good video for ghosty, its not all blurred. :o

The boat goes extremely well too. O0
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Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

andrewh

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Re: Higgins Hellcat
« Reply #8 on: June 12, 2008, 02:19:30 PM »

Glyn,
Bother, another one for the build list!

Given your awareness of the weight/speed balance have you given any thought to lithium cells?

I (abundantly) do not wish to light a fuse with those who hold strong views, but there are plenty of Li-ion cells around with good voltage and capacity (and the deeeeeply safety conscious can go for the Saphion cells)

I use my aircraft packs of Lipo cells, with basically the same brushless motors (also very light) and get very sprightly performnce on 2 cells (8V) and SP400 running gear . 
I also use reclaimed Li-ion cells recovered from laptops connected up as 2S2P and carefully charged on a lithium charger.

andrew
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jviewing

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Re: Higgins Hellcat
« Reply #9 on: June 12, 2008, 03:16:29 PM »

Hi son Johnathan (13) is building the model fron this months model boats free plan. After much discussion he has chosen a direct drive with the prop and rudder set about 10mm further back and a shorter prop shaft keeping the motor a 540 in relativly the same place as the plan. He is very keen to detail the model and say's that speed in not the issue.
Any comments? as I am sure he would welcome Glynn's or any experienced modellers input.
Best regards Jeremy
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GG

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Re: Higgins Hellcat
« Reply #10 on: June 12, 2008, 05:02:19 PM »

Sorry guys, I've no experience with lithium cells.  I would be worried about overpowering this type of model, the video was taken when the model had the standard 540 motor, with the racing motor it was a shade more exciting but still safe!
Altering to direct drive and a smaller propeller might be OK but I've always found that geared drive to a larger and probably more efficient propeller gives me a good combination of speed and duration.
If speed is not called for I would be tempted to (as in the Miami Crashboat) use a Speed 400 motor and high capacity Ni-mh cells. 
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andrewh

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Re: Higgins Hellcat
« Reply #11 on: June 25, 2008, 01:42:51 PM »

Glyn,

The video and borrowed copy of the comic and plan have grabbed me:  You have a lot to answer for ;D

I suspect that I will go for the geared 500 motor option, but most of the motors of that size I have are electric flight motors - I suspect that revs will not be an issue, but duration might be!

If  the end of the propshaft is available I might also try a brushless outrunner in direct drive with li-ion batteries (liberated from laptop power packs). 

But first build a hull....

Thanks for the design - hope there are many built!
BTW-  have there been a lot of the original PT boats built?  I bought the mag in Christchurch airport (NZ) solely for the plan

regards
andrew
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GG

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Re: Higgins Hellcat
« Reply #12 on: June 25, 2008, 11:16:59 PM »

Andrew,
             Good luck with your build, I look forward to seeing how it turns out.

As to the Elco PT boat plan, I have no idea how popular it is.  To be honest the published plan was faulty as the !*$!!^*# draughtsman who redrew it clearly felt he knew more about it then the designer.  A successful model can be built from this plan but it still leaves a bad taste in my mouth.

To be fair with "Model Boats", since this incident they have always sent me a copy of the plans to check for any mistakes/omissions before it gets published.

Regards, Glynn
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andrewh

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Re: Higgins Hellcat
« Reply #13 on: June 26, 2008, 01:19:32 PM »

Glyn,

I'm an aeromodeller,  I expect very little from plans, and definitely not symmetry or panel shapes. 
My first indoor model was Walt Mooney's Sparrowhawk where the wings are of different sizes (one was quite small , almost nothing at all, and the ..........)

What should I be looking out for on the Elco PT published version?

It  REALLY sounds as if you need a proving builder to verify that the published plan is more-or-less numpty proof ;D
Am I first in a queue now forming?

andrew
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GG

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Re: Higgins Hellcat
« Reply #14 on: June 27, 2008, 06:31:04 PM »

Andrew,
            Basically the "draughtsman" who redrew the Elco PT Boat plans decided that you did not need to allow for the thickness of the hull sheeting. This enabled him to avoid drawing out a couple of pieces at the right size and shape.  As a result a hull built from this plan does not match my prototype and needs extra work to make things fit.  Even so, models built this way do seem to work but it could have been a complete disaster!

With the magazine letting me check the plans against my copies, I do not think there is a need for, nor would there be time for a "proving build".

By the way I'm an aeromodeller too, still indulge in the local fields, much to the amusement of the locals.

Regards, Glynn
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andyn

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Re: Higgins Hellcat
« Reply #15 on: July 06, 2008, 04:04:54 PM »

My bulid is now drawing to a close, having just put one side of hull sheeting on.

I would like to thank you very much for designing this boat, it has been very enjoyable to build and quite challenging also to get the details done nicely. If all goes well it should be at the lake next sunday or maybye even thursday.

Shall post some pics of it when it's done.

Today I picked up someones surplus copy of a Model boats' from June 2003, with the free plan your Carrier Uss Bodega Bay, and have decided to build this next (possibly over the winter), anything I should know about it? any further build notes?

Cheers for the Hellcat

Andy
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andyn

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Re: Higgins Hellcat
« Reply #16 on: July 08, 2008, 06:17:33 PM »

Finished!

The first thing you will notice is it's a different colour, obviously due to personal preference, and the lifeboat is a rib not a dinghy.
The rear cannon has a micro servo under it as promised, and moves with the rudder.
Been in the bath, floats nicely with no leaks, and has tons of power, most of the water that was in the bath is now up the wall  O0
Used a slightly bigger rudder than on the plan (for stability) with a smaller amount of movement.

Looking forward to thursday!




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andrewh

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Re: Higgins Hellcat
« Reply #17 on: July 09, 2008, 05:06:24 PM »

Beautiful boat, Andy

But how did it happen that you built it on a tidy version of my workbench without me noticing?

Did you get to break out the champagne, and which part of the world are you in?

andrewh
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andyn

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Re: Higgins Hellcat
« Reply #18 on: July 10, 2008, 01:22:20 PM »

Havent broken out the champagne yet, that (hopefully) will be in around 2 hours from now, depending on whether the canoeing people are off our lake,  (the normal lake they go on is drained at the moment for renovation)and probably whether anyone else turns up.

As for the workbench, I'm magic  ;)
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andyn

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Re: Higgins Hellcat
« Reply #19 on: July 13, 2008, 01:38:09 PM »

Didn't manage it on thursday, so it got a run today. Goes very well, a bit twitchy and doesn't turn at full throttle too happily, but over all extremely pleased with it.

Got a bit wet when I handed it over so i could take some photos, it was put staight into full reverse (it was drifting into shore) and the back dug in. got a bit of water inside but nothing serious. Those spray rails really work well and are worth the fuss of getting them on.

Plains straight away from stanstill and can get up from anywhere through the throttle range, at a somewhat strange angle, the back stays in the same place on the water but the nose lifts until the front half of the hull is completely out of the water. This is probably due to the positioning of the battery, which may need some experimentation.

which part of the world are you in?

andrewh

I'm in Stevenage, England.

I understand you are using straight drive? I used an X45 prop but it would probably be better off with an X40

This boat shall hopefully be used for years to come, it's great fun O0
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GG

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Re: Higgins Hellcat
« Reply #20 on: July 13, 2008, 09:16:09 PM »

Congratulations Andyn,
 Yes it is a model that needs to be consciously driven 100% of the time, gentle turns are OK at full speed but tight turns call for slower speeds.  You might find it makes life easier if you have a transmitter that can reduce the servo travel around neutral (Adjustable Responce Curve) or use dual rates.

The best high speed trim appears to be with the model running more or less level, perhaps the bows slightly high.  Only the curved part of the bows should be clear of the water and the spray strips will keep it running cleanly.  As you have found out, slow astern only!

Definately not suitable for the modeller who cannot use proporional RC correctly, that is smooth commands not full power/rudder with nothing inbetween.
Glynn
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andrewh

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Re: Higgins Hellcat
« Reply #21 on: July 14, 2008, 01:23:54 PM »

Andy - congratulations, sounds like a very successful maiden flight!

Sounds too from your comments and Glyn's that she needs to be flown with sensitivity (a bit like a plane).  I seem to remember Peter Miller mentioning the characteristic sitz of the Higgins boats - bow (just) clear of the water at speed.

Glyn, I hope you will forgive me in advance, I aim to do a VERY SWIFT version of a Hellcat. 
I am running a bare-deck version of Richard Webb's   Portsmouth harbourmaster's launch using home-made brushless ratmotor and S400 running gear.  In many respects it could be a stand-way-way-off PT hull so it will get upperworks in balsa or foam, tubular torpedoes and a suitable marine paint job.  It goes like stink on 2 Liion cells, making a weird whistling noise
I will claim only that it is INSPIRED by you and your plan

action and pictures folllow
and that reminds me;
Andy.  Pics?
andrew
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andyn

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Re: Higgins Hellcat
« Reply #22 on: July 14, 2008, 02:26:49 PM »

I'm afraid that the pics are a bit naff as i took them on my phone, which isn't all that good at moving pics, however next time i shall take a decent camera with me.


It does need some careful conrolling, but I'm used to that as I've been flying a Shock-Flyer for the last two years (if you're not sure what one is, tap it into youtube). It really does need some careful controlling and I can't be asked with exponential!

The reason it sits so far back on the plane is because as I did straight drive with propshaft and mount in the same place as the plan, I assumed that the battery would need to be further back. The positioning is aadjustable, but where I had it yesterday was overcompensation. The high level of pitch was only at high throttle, but at scale speeds it looked accurate.

More pics to follow.



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andrewh

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Re: Higgins Hellcat
« Reply #23 on: July 14, 2008, 02:37:20 PM »

Thanks very much for these, Andy - they were taken under wartime conditions, at a secret proving location!

If you are a shock flyer (I tend to do indoor FF and scale flying) you could use some of your 3S Lipo packs to help her move out - , and maybe a small brushless for added efficiency;  or would more power less weight be too much of a good thing?

We should never forget one of Hailwood's maxims, that the throttle goes both ways

andrew
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andyn

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Re: Higgins Hellcat
« Reply #24 on: July 14, 2008, 04:33:57 PM »

I may stick a lipo in, we'll see.

That would mean I would need a different ESC as the current one can't do LiPo's
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